Laubmoos. Die Zellwand wirkt als semipermeable Membran für größere Moleküle. Im hypertonischen Milieu wird der Zelle Wasser entzogen. Bei der Zytorrhyse bleibt der Protoplast der Zellwand angelagert, die sich eindellt; in kleinmolekularer, hypertonischer Lösung setzt Plasmolyse ein.

The film deals with cytorrhysis in leaf cells of the moss Hookeria lucens which is caused by the withdrawal of water from the cells and thus the cell wall is so flexible here that it can follow the contracting protoplasts. Cytorrhysis occurs in the natural habitat and is here a factor of drought resistance, since the plasma is prevented from tearing from the cell wall, thus preventing the death of the cell. Like many mosses, Hookeria has such a dense cell wall that substances with a large molecular volume cannot pass through it. If, for example, leaves are laid in hypertonic saccharose solutions, water is withdrawn from the whole cell; the cell wall is here the semi-permeable barrier. Here too, the thin flexible cell wall follows the vacuole contracting due to the water withdrawal and becomes dented. Cytorrhysis images emerge which are very similar to those formed by dessication. The cells can be plasmolyzed by the subsequent addition of a hypertonic solution of a small molecular substance. A normale plasmolysis is shown for comparison.